Abstract [en]

This report is part of a Master thesis project in the subject of Product Development. The workincludes a case study which was carried out at RTGA, Scania CV AB in Södertälje. The workcomprises 30 credits and was conducted by a student from Mälardalen University during thespring semester 2015. The report has been prepared in two versions; one for Scania CV AB anda generalized version where sensitive company specific information has been censored.

The development of vehicle engine performance progresses in a rapid pace. This progressinclude increased engine power and improved technical features for emission control. This alsogoes for the requirement on performance of cooling systems in heavy trucks, which has tohandle dissipation of the increased power. Vehicles with powerful charge air coolers however,runs a high risk of being affected by iced condensation in the charge air cooler at low ambienttemperatures. The ice build-up results in a pressure drop in the charge air cooler with a loss ofengine performance as a consequence. Scania's solution to the problem is a so called radiatorblind designed to reduce the cooling air flow through the charge air cooler to the extent thatice build-up does not occur. The blind is mounted manually in front of the cooler package whenthe ambient temperature is expected to be below 5 °C.

There are also other advantages to limit the outer cooling air flow passing through the coolingpackage. The cooling systems in heavy trucks are usually oversized for normal operatingconditions such as highway cruising, which means that maximum cooling is not required inthese situations. By reducing the airflow through the cooler package, the vehicle's total airresistance is reduced, which can be utilized in order to reduce fuel consumption.

To obtain a good balance between aerodynamics and cooling performance, and to counteractthe problem of ice build-up in the charge air cooler, there was a desire for an adjustable radiatorcoverage which would be able to regulate the airflow through the vehicle's cooling packagewhen needed.

This work includes a case study in which various product development tools are used toinvestigate different concept solutions, designated for a specific truck model. Computationalfluid dynamics (CFD) are used to evaluate and validate the concept’s functionality andcomparing them to different reference models.

The results reveal that the final concept functionality is consistent with the one used today, andthat the cooling air flow is not significantly affected when maximum cooling capacity is strivedfor. The results of the aerodynamic flow simulation also indicate that the vehicle's total airresistance can be reduced by - Drag Counts (DC) at the speed of 90 km/h and 0° yaw angle.This means that fuel consumption in the specific operating case, as rule of thumb, is assumedto be reduced by - % for the specific vehicle.